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Biomedical subjects

R N Maini

Publications and source records attributed to R N Maini.

At least 109 records · Page 6Linked to original sources
PubMed1995

Cytokine expression in chronic inflammatory disease.

In chronic inflammatory diseases, typified by rheumatoid arthritis, we speculated that upregulation and/or disregulation of cytokine production in inflamed tissue might contribute both directly and/or indirectly to the pathology in the synovial joint tissue. This chapter summarises studies performed principally by our own group over the last 9 years or so, but also by others in the field who have investigated the expression of cytokines in RA. From our studies we identified one particular cytokine, tumour necrosis factor alpha (TNF alpha) as an important, 'pivotal', molecule in the disease process. This concept has led to the initiation and completion of the first successful clinical trials in RA patients to verify this hypothesis, using a neutralising antibody to TNF alpha.

Arthritis, Rheumatoid↗
PubMed1995

Gene therapy of rheumatoid arthritis via cytokine regulation: future perspectives.

Following many years of research using isolated human tissues and animal models, sufficient knowledge concerning rheumatoid arthritis has accumulated so that novel immunotherapies have been proposed. Biological agents are being tested in clinical trials and include antibodies to T cells and cytokines. Currently the most promising of these is intravenously administered neutralizing anti-TNF antibody. In order to establish disease modification, however, therapy needs to be delivered continuously over the long term. The prospect of delivering cytokine inhibitors as genetic material (naked DNA), viruses or in engineered autologous cells is considered as one option for achieving this goal. We compare two strategies, firstly, using immobile cells such as fibroblasts, myoblasts or keratinocytes, and secondly, the migratory cells of the immune system. The former provides a reservoir of systemic delivery of the therapeutic protein whereas the latter provides targeted delivery determined by the antigen specificity of the immune cells. Early validation has begun in animal models of rheumatoid arthritis.

Animals↗
PubMed1995

Interferon-gamma and epithelial cell activation in Sjögren's syndrome.

We have examined the hypothesis that interferon-gamma (IFN-gamma) and its interaction with epithelium may play a role in the perpetuation of inflammation in Sjögren's syndrome (SS). Labial salivary gland primary cell cultures from 16 patients with primary SS (pSS) and eight cultures from patients with SS symptoms but histologically normal biopsies were examined for expression of HLA-DR and cytoplasmic La (SS-B). Epithelial HLA-DR expression was found in 80% of cultures from pSS patients and 38% of those from patients not fulfilling diagnostic criteria. Cytoplasmic La was detected in 50 and 38% of cultures, respectively. Treatment of 14 of the cultures with IFN-gamma increased HLA-SR and cytoplasmic La expression above that of untreated cultures. Depletion of IFN-gamma using neutralizing antibody had the reverse effect. These findings suggest that the perpetuation of chronic inflammation of pSS may be due to the induction of HLA-DR and La antigen expression on epithelial cells by IFN-gamma.

Adult↗
PubMed1995

Antibodies to the 65 kDa mycobacterial stress protein in west Africans with rheumatoid arthritis, tuberculosis and malaria.

We have studied IgG antibodies to recombinant mycobacterial 65 kDa heat-shock protein in West African rheumatoid arthritis (RA) patients and local control groups, including those with tuberculosis or malaria. Mean levels were higher among the patients with RA than among healthy controls, but did not achieve statistical significance. Our findings may relate to the level of mycobacterial exposure in West Africa.

Africa, Western↗
PubMed1995

Arthritis in scleroderma.

Thirty-four patients (24 females and 10 males) selected from 300 consecutive patients with established systemic sclerosis (SSc), with a current or past history of articular symptoms, were clinically documented and further studied using thermography and bone scan to define the pattern of arthritis. Clinical evidence of synovitis was observed in 30 (88%) and joint inflammation was detected in 31 (91%) by the above-mentioned imaging techniques. A distinctive subset of 10 patients with deforming arthritis was characterized in which seven (70%) patients fulfilled criteria for both rheumatoid arthritis and SSC; three of these satisfied the criteria for diagnosis of CREST, but none met the criteria of mixed connective tissue disease. These patients, as a group, when compared with the rest showed limited skin involvement (skin score of 19 +/- 11 vs 33 +/- 14; P < 0.05) and were positive for rheumatoid factor (80 vs 13%; P < 0.05) and anticentromere antibodies (37 vs 4%; P < 0.05).

Adult↗
PubMed1995

Anti-La (SS-B) but not anti-Ro52 (SS-A) antibodies cross-react with laminin--a role in the pathogenesis of congenital heart block?

Cross-reactions between maternally derived autoantibodies and fetal cardiac antigens have been postulated to play a role in the pathogenesis of congenital heart block (CHB). We have explored the cross-reactivity of autoantibodies to the small ribonuclear autoantigens, La/SS-B and Ro/SS-A, with laminin, the major component of cardiac sarcolemmal membrane using affinity-purified antibodies from patients with Sjögren's syndrome (SS). Anti-La antibodies purified from eight of 10 patients cross-reacted significantly with mouse laminin by ELISA. In contrast, purified antibodies to Ro52 from the same 10 patients showed little or no binding to laminin. Laminin inhibited up to 70% binding of anti-La antibodies to La antigen, and La inhibited up to 65% binding of anti-La antibodies to laminin. The cross-reaction was further examined on cryosections of 10 human fetal hearts aged from 8.7 to 14.9 weeks of gestation, two normal adult hearts, and one pathological adult heart with a diagnosis of dilated cardiomyopathy. Anti-Ro52 antibodies did not bind to the surface of cardiac cells. However, anti-La antibodies from seven of 10 patients tested bound to the surface of fetal myocytes from hearts aged 9.4 to 14.9 weeks of gestation, and also to the myocytes from the pathological adult heart but not to normal adult hearts. Preincubation with La antigen abolished the binding of anti-La antibodies to the surface of adult heart myocytes with dilated cardiomyopathy, and pre-incubation with mouse laminin could partially block this binding. These results suggest that molecular mimicry between laminin and La, but not Ro52, may act as a target for specific maternal autoantibodies, and contribute to the pathogenesis of CHB at a critical stage during fetal cardiac development.

Adult↗
PubMed1995

Beneficial effects of tumour necrosis factor-alpha (TNF-alpha) blockade in rheumatoid arthritis (RA)

The biological properties of TNF-alpha make it a candidate therapeutic target in RA. Our studies have demonstrated that TNF-alpha and its receptors are up-regulated and co-expressed in the synovium and cartilage-pannus junction of RA joints. Neutralizing TNF-alpha antibodies reduce the production of the many pro-inflammatory cytokines, including IL-1 and granulocyte-macrophage colony-stimulating factor (GM-CSF), produced by mononuclear cells from RA in culture. When injected into DBA/1 mice with collagen-induced arthritis and TNF-alpha transgenic mice with arthritis, anti-TNF MoAbs decrease inflammatory damage of joints. Clinical trials employing cA2, a chimaeric anti-TNF-alpha MoAb, in open-label and randomized placebo-controlled studies have demonstrated a dose-dependent efficacy with impressive improvement in disease activity and acute-phase responses lasting several weeks. We conclude that TNF-alpha is a critical mediator of inflammation in RA, and is an important therapeutic target in this disease.

Antibodies, Monoclonal↗
PubMed1995

Monozygotic rheumatoid arthritis twin pairs express similar levels of conserved immunoglobulin V gene in polyclonal rheumatoid factors irrespective of disease status.

The degree of polyclonal RF heterogeneity was assessed in diseased and non-diseased twins with rheumatoid arthritis (RA). The distribution of variable region determinants encoded by a set of immunoglobulin germline, or minimally mutated germline, genes within IgM RF, IgG RF and IgA RF isotypes was determined by ELISA using specific mouse monoclonal antibodies (MoAb) in fractionated plasma from 12 members of six monozygotic twin pairs with RA. The results reveal that at least 40% (range approximately 18-87%) of IgM RF are encoded by a small set of approximately 10 genes from the VH1, 3 and 4 families. Furthermore, a significant proportion of IgG RF and IgA RF (approximately 30%) are also encoded by these same genes. Comparison with RF-negative fractions of immunoglobulins showed that the examined variable region determinants were overrepresented in the RF fractions. The level of expression of the variable region determinants in RF were generally similar within twins but different between unrelated twin pairs irrespective of disease status. The variability of VH gene usage between unrelated individuals suggests that the level of expression and regulation of the variable region determinants may be genetically regulated or influenced by common environmental factors.

Adolescent↗
PubMed1995

TNF inhibitors are produced spontaneously by rheumatoid and osteoarthritic synovial joint cell cultures: evidence of feedback control of TNF action.

We have proposed the hypothesis that tumour necrosis factor alpha (TNF-alpha) has a pivotal role in the pathogenesis of rheumatoid arthritis, based on in vitro observations that in RA synovial joint cell cultures removal of TNF-alpha, inhibited other potentially pathogenic cytokines such as the equally proinflammatory cytokine interleukin 1 (IL-1) and the macrophage activating factor, GM-CSF. Here we describe that in both rheumatoid (RA) and osteoarthritic (OA) synovial cultures there is a homeostatic mechanism to regulate the activities of TNF-alpha. This concept is based on several observations. First in these synovial joint cell cultures the substantial discrepancy between the levels of bioactive and immunoreactive TNF-alpha indicates the presence of an inhibitor. Second, TNF binding proteins are produced spontaneously, which are the soluble variants of surface p75 and p55 TNF receptor. The amount of soluble TNF receptors (sTNF-R) produced varied between cultures; p75 sTNF-R was more abundant than p55 sTNF-R (as detected by ELISA), and both were produced at higher levels by RA synovial joint cells in culture, compared to OA cultures. These TNF binding proteins act as endogenous inhibitors of TNF-alpha, since blocking their activity in synovial joint cell culture supernatants with MoAb to p55 and p75 sTNF-R enhanced their cytotoxic activity in the TNF bioassay. The regulation of production of these sTNF-R in synovial joint cell cultures is important as the balance between TNF-alpha and sTNF-R production may determine the outcome of the inflammatory process.

Arthritis, Rheumatoid↗
PubMed1995

Monoclonal anti-TNF alpha antibody as a probe of pathogenesis and therapy of rheumatoid disease.

Rheumatoid arthritis is a common cause of chronic disability for which current therapies are of limited value in controlling the disease process and outcome. Our initial approach to understanding the pathogenesis of RA and defining a novel therapeutic target was to investigate the role of cytokines by blocking their action with antibodies on cultured synovial-derived mononuclear cells in vitro. These investigations suggested that neutralization of TNF alpha with antibodies significantly inhibited the generation of other pro-inflammatory cytokines also over-produced, such as, IL-1, GM-CSF, IL-6 and IL-8. The implication that blockade of a single cytokine, TNF alpha might have far-reaching effects on multiple cytokines and thereby exert significant anti-inflammatory and protective effects on cartilage and bone of joints, was tested in arthritic DBA/1 mice immunized with collagen II. Impressive amelioration of joint swelling and joint erosions in this model encouraged clinical trials with a monoclonal anti-TNF alpha antibody. The cA2 chimeric anti-TNF alpha high-affinity antibody was initially tested in an open-label study at a dose of 20 mg/kg on 20 patients, with substantial and universal benefit. Subsequently, a randomized placebo-controlled double-blind trial was performed on 73 patients comparing a single intravenous injection of placebo (0.1% human serum albumin) with two doses of cA2. Using a composite disease activity index, at 4 weeks post infusion, 8% of patients receiving placebo improved compared with 44% receiving 1 mg/kg cA/2 and 79% receiving 10 mg/kg. Between 2 to 4 repeated cycles of cA2 were administered to 7 patients and all patients showed improvement of a similar magnitude with each cycle. These data support our proposition that TNF alpha is implicated in the pathogenesis of RA, and is thus a key therapeutic target. Monoclonal anti-TNF alpha antibodies control disease flares and are candidate agents for longer-term control of RA, although repeated therapy with cA2 is associated with anti-idiotypic responses in 50% of patients and a trend toward shortening of the duration of response. In the DBA/1 arthritic mice, synergy of action of anti-TNF and anti-CD4 is observed together with suppression of an anti-globulin response, indicating one way in which benefit might be augmented in the future.

Animals↗
PubMed1995

Sequence analysis of immunoglobulin heavy-chain variable region genes from the synovium of a rheumatoid arthritis patient shows little evidence of mutation but diverse CDR3.

To gain insight into the nature of B-lymphocyte responses in the synovium of rheumatoid arthritis (RA) patients, we amplified and sequenced immunoglobulin heavy-chain variable region genes expressed in seven IgM and three IgG-secreting synovial-derived hybridomas established from one patient. Each hybridoma V-region was encoded by unique VH-D-JH combination demonstrating that none of these hybridomas derived from clonally related B-lymphocytes in vivo. The expressed VH genes closely resembled (95.6%-100% homology) known germline VH genes in most hybridomas, including VH genes frequently used to encode autoantibodies. The antibodies produced by these hybridomas, with the exception of one IgM rheumatoid factor, did not bind to any of a large panel of autoantigens in enzyme-linked immunosorbent assay (ELISA), immunoblotting and immunofluoresence, suggesting that frequent expression of 'autoantibody-associated' VH genes does not correlate with detectable autoreactivity in this patient. Hybridoma CDR3 DNA was diverse in length and gene composition. Conserved heavy-chain cross-reactive idiotypes were expressed on 4/7 IgM- and 2/3 IgG-secreting hybridomas. The close similarity of expressed VH genes to germline counterparts of these hybridomas suggests that polyclonal activation is a prominent mechanism in B-lymphocyte activation in the synovium of this rheumatoid arthritis patient.

Arthritis, Rheumatoid↗
PubMed1995

Successful therapy of collagen-induced arthritis with TNF receptor-IgG fusion protein and combination with anti-CD4.

We have previously shown that anti-tumour necrosis factor (TNF) monoclonal antibody (mAb) ameliorates established collagen-induced arthritis and that the efficacy of this form of treatment can be enhanced by concurrent anti-CD4 treatment. Here we assess the efficacy of a human p55 TNF receptor-IgG fusion protein (p55-sf2), given alone or with anti-CD4 mAb. TNF receptor-IgG fusion protein (100 micrograms) suppressed paw swelling and limb recruitment in established arthritis and reduced the incidence of erosions in the proximal interphalangeal joints from 92% to 50%, which was comparable to 41% erosions using anti-TNF mAb. Methylprednisolone acetate (4.2 mg/kg/week) reduced clinical signs of inflammation in a manner comparable to TNF blockade but had little effect on the incidence of erosions. Co-administration of anti-CD4 and TNF receptor-IgG led to an even greater therapeutic effect than TNF receptor-IgG alone, with the incidence of erosions being reduced from 100% to 17%. Serological analyses showed that the beneficial effects of anti-CD4 and TNF receptor-IgG could be partly explained by the ability of anti-CD4 to prevent a neutralizing antibody response. These results confirm the importance of TNF in destructive inflammatory arthritis and demonstrate the feasibility of therapeutically targeting TNF with a form of TNF receptor. Finally, the findings confirm the beneficial effects of TNF-targeted therapy coupled with anti-CD4 therapy.

Animals↗
PubMed1994

Randomised double-blind comparison of chimeric monoclonal antibody to tumour necrosis factor alpha (cA2) versus placebo in rheumatoid arthritis.

Tumour necrosis factor alpha (TNF alpha) is a critical inflammatory mediator in rheumatoid arthritis, and may therefore be a useful target for specific immunotherapy. In support of this hypothesis, we previously observed beneficial responses in patients with active rheumatoid arthritis after open-label administration of a chimeric monoclonal antibody to TNF alpha (cA2). We now report the results of a four-centre, randomised double-blind trial of a single infusion of 1 or 10 mg/kg cA2 compared with placebo in 73 patients with active rheumatoid arthritis. The primary endpoint of the study was the achievement at week 4 of a Paulus 20% response, an amalgam of six clinical, observational, and laboratory variables. Intention-to-treat analysis of data from individual patients showed only 2 of 24 placebo recipients responding at this time, compared with 11 of 25 patients treated with low-dose cA2 (p = 0.0083) and 19 of 24 patients treated with high-dose cA2 (p < 0.0001). Over half of the high-dose cA2 patients responded by the more stringent 50% Paulus criteria at this time (p = 0.0005). The magnitude of these responses was impressive, with maximum mean improvements in individual disease-activity assessments, such as tender or swollen-joint counts and in serum C-reactive protein, exceeding 60% for patients on high-dose treatment. There were two severe adverse events. 1 patient on 1 mg/kg cA2 developed pneumonia ("possibly" treatment-related) and 1 on 10 mg/kg had a fracture ("probably not" treatment-related). The results provide the first good evidence that specific cytokine blockade can be effective in human inflammatory disease and define a new direction for the treatment of rheumatoid arthritis.

Adolescent↗
PubMed1994

Repeated therapy with monoclonal antibody to tumour necrosis factor alpha (cA2) in patients with rheumatoid arthritis.

Our in-vitro, animal, and early clinical data suggest that tumour necrosis factor alpha (TNF alpha) is an important target for specific biological therapy in rheumatoid arthritis. We report the results of repeated treatment with a chimeric monoclonal antibody to TNF alpha (cA2) in patients having disease flares. 7 patients originally enrolled in an open-label trial completed two to four cycles, each of which was followed by a good clinical response, with median improvements in the swollen-joint count and C-reactive protein exceeding 80%. cA2 may be useful therapy in the control of acute disease flares in rheumatoid arthritis and treatment programmes including cA2 may be effective in the long-term management of this disease.

Antibodies, Monoclonal↗
PubMed1994

Crystallization and preliminary X-ray analysis of the Fab fragment of a human monoclonal IgM rheumatoid factor (2A2).

Crystals of the Fab fragment of a human monoclonal IgM rheumatoid factor have been obtained and are suitable for X-ray structure determination. This molecule, derived from the synovial B cells of a patient with rheumatoid arthritis, is an autoantibody with specificity for IgG Fc. The crystals have space group P2(1), cell dimensions a = 69.0 A, b = 76.6 A, c = 98.8 A and beta = 90.6 degrees, and diffract to a resolution of at least 2.8 A.

Antibodies, Monoclonal↗